We report on the fabrication, piezoresistive readout, and frequency response of doubly-clamped c-axis gallium nitride (GaN) nanowire (NW) resonators that show mechanical quality factors exceeding 10,000. The devices are fabricated using a combination of lithographic patterning and dielectrophoresis to suspend wires across 10 micrometer gaps. An electrostatic gate induces NW vibration, which is electronically detected via NW piezoresistance. The naturally occurring range of NW diameters results in lowest beam resonances in the range of 9-36 MHz, consistent with a Youngs modulus of roughly 300 GPa. Mechanical quality factors, Q, as high as 16,000 under vacuum at 11 K are observed. Selective variation of NW temperature by local Joule heating while maintaining cold mechanical clamps demonstrates the dominant role of the polycrystalline metallic end clamps in the room-temperature mechanical dissipation.
Citation: Journal of Vacuum Science and Technology B
Issue: Sep/Oct 2011
Pub Type: Journals
GaN nanowires, nano-mechanics, nano-mechanical resonators, electro-mechanical resonators, piezoresistivity